I once asked a well known and respected Rosh Yeshiva about R’ Falk’s sefer. I won’t say who the Rosh Yeshiva is, because if people knew he said it, the backlash against him would be terrible.
He said, “That sefer is only good if you want to scare people away from tznius! It contains every chumrah ever thought up and presents it as basic halachah that is required from everyone. I don’t recommend it to anyone!”